1. Field of the Invention
The present invention relates to a document retrieval system and more particularly to a subsystem of a document retrieval system for receiving a list of documents (or texts) selected from a text base and providing a list of keywords ranked in order of importance in the selected text group.
2. Description of the Prior Art
In order to retrieve one or more texts which best contain desired information in a conventional text retrieval system, the user has to input an appropriate query request by using keywords which best characterize the desired text(s). However, such keywords hardly occur to the user. It is especially true to those who are not familiar to the field of the desired text(s). For this purpose, various measures have been taken so far which help the user with his or her further searches by displaying related words associated through a kind of dictionary (e.g., a thesaurus, a synonym dictionary, etc.) with the keywords entered by the user. However, it is difficult to obtain related words responsive to characteristics of the desired text(s) because the obtained related words are dependent on a dictionary which has been statically prepared in advance. Further, making a query request by using the obtained related words not always results in a successful retrieval of at least one desired text.
It is therefore an object of the invention to provide a related keyword generating system, used in a document retrieval system, for receiving a list of documents (or texts) selected from a text base and providing a keyword list of words ranked in order of importance in the selected text group so as to facilitate an effective and quick document retrieval.